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454 engine thump Johnny 7-31-02  
I have a 1973 Sportscoach with a 454 Chevy engine. On a recent trip I started the engine in the morning only to hear a loud sharp thump coming from the engine. We were in Myrtle Beach so the resourses were limited. Finally I found a shop to look at it. They told me it needed a crankshaft kit and the transmission had to be removed in order to replace the crank from the bottom without pulling the engine. estimate: $1200. Fine. We rented a car and finished the vacation returning to pick up the motorhome. Finished. Bill:$2300 which included a crank kit new timing chain transmission seal and water pump. OUCH. 92000 mile engine. It was warmed up and ready to go when we got there. Next problem. The next morning it thumped again. SAME PROBLEM! Called the crank installer and he blew me off. We were 300 miles away. He said bring it back. Not likely. Now we are home and every time I start it cold it has this horrible loud thumping noise. By the way the oil pressure is always 60 running and 40 at idle and there is no metal in the oil or the filter. Local Chevy dealer said it sounded like main bearings but couldn't explain the fact that there was no metal in the oil or filter. Any suggestions? This is an old coach not worthy of a $7000 engine job.
Re: 454 engine thump Joe 7-31-02  
No metal in the oil, or no visible metal in the oil? If a crank kit was installed and it still has the same noise there could be a problem with the block where the mains go, but first I would do some checking. Two things come to mind.....a cam and lifter problem where as worn lifters will cause the cam to "Walk" back and forth making your "Thumping" noise. The other is a noisy fuel pump. This doesn't happen often, but it happens. Cheapest thing to check...remove or have somebody remove the bolts for the fuel pump even leaving the lines attached and start the engine cold. See if the noise is still there or not. A stethescope would work too, but fuel pumps normally will be noisy to a stethescope. If that doesn't work and the noise is still present replace the fuel pump and let the engine sit until you think it will make the noise. Get a long piece of heater hose and hold one end to the timing cover located behind the water pump and the other to your ear. See what happens.
Re: 454 engine thump Bob 7-31-02  
Check motor mounts..torgue on engine as it starts or drops in gear will thump. Engine will move on mounts. If rubber bushings are worn, or mount broken???
Re: 454 engine thump jc 8-1-02  
Was the motor ran at high rpm? (hammered)
Re: 454 engine thump Chuck Bscherer 8-7-06  
What is the normal running and idle oil pressure of a Chev 454. I have a 1982 Fleetwood RV with a 454.
Re: 454 engine thump Johnny 8-1-02  
Tried the fuel pump last night at the same time tried the heater hose thing. The noise was loud in the heater hose. What next?
Re: 454 engine thump Robert 7-31-02  
Is the sound constant or corresponds to engine speed? Another thing to check would be to hook up a timing light. If the noise is in sync with the timing light then the cause might be at the bottom end. If the noise is twice as fast, then it could be the top end that's causing the noise. This will narrow it down. How well was the engine running before the noise happened. Usually, a rod knock or main bearing failure comes when the engine is getting tired. Unless a wrist pin retainer has failed. But no metal in the oil is somewhat puzzeling.
Re: 454 engine thump Johnny 7-31-02  
Knock or double knock I can't tell. It just knocks. The engine runs great at all times.
Re: 454 engine thump Johnny 8-1-02  
No broken mounts. This is a metal to metal noise that goes away soon after first start up.
Re: 454 engine thump Johnny 8-1-02  
Hammered, like pulling a 9000 motorhome dowwn the road sometimes going 70 mph @ 4200 rpm for 92000 miles? Yes.
Re: 454 engine thump Joe 8-1-02  
Well, now we have determined that the noise is in the front of the engine. Now it gets complicated. By your evaluation of the no metal in the oil I'm going to suggest an oil analisys. We have a company that does it for $35. I'm thinking that if there is metal, it is so minute that you can't see it but it is there. There is nothing else to check easily. You would have to remove valve covers, water pump, timing chain cover, oil pan. I'm not sure of your capabilities. First would be valve covers and measure the lifter stroke. At the same time you have the valve covers off you might notice a glitter like deposit in the bottom of the head. Not knocking anybodys work, but you can't replace the crank from the bottom and not pull the engine and flush out all the metal from all the oil passages and the oil cooler. Metal would be everywhere...lifters...push rods.....everywhere oil accumilates. First, run the engine for 5 or so minutes and let it sit for a few minutes. Than drain about a quart in a clean pan. Take the oil out into the sunlight and lean the pan back and forth to see if there is a glitter in the oil. Your oil pressures are perfect. Something doesn't match here.
Re: 454 engine thump Johnny 8-1-02  
Joe I think you have something there. My brother in law is a ford truck mechanic and he is on vacation too so we are really digging into this. We checked the rocker lift and three were much lower than the rest. Next we pulled the fan water pump and timing cover. Pieces flying everywhere. When we started the engine the thump sounded right there. He held a brass punch against the top gear and the noise went away. He let it go and it came back. What next? I'm running out of vacation days but this has been an experience.
Re: 454 engine thump Joe 8-1-02  
Well, Sir, it is time to go buy a cam kit and all the other necessary parts to do this job correctly. Keep that Ford mechanic will need him. Remove the radiator, distributer,intake manifold, rockers, push rods, timing gears and chain, camshaft very carefully as not to nick the cam bearings, drop the oil pan, flush out the oil cooler, flush, wash, clean, blow out, everywhere oil can go. Check the bearings (rod and main) check the cam bearings and if all is well and CLEAN CLEAN CLEAN....then lube and install your new cam and lifters. We submerge the lifters in light oil and pump them up before installing them. Install the timing chain and gears.Then using the special camshaft lube, install the lifters, push rods, and rockers. Remove the spark plugs and rotate the engine to the low side of the cam lobe on each cylinder and adjust for zero lash (When you can just easily rotate the push rod) and tighten the rocker 1/2 turn. You will set them again after it is running. Reassemble the engine leaving off the valve covers.If you can beg, borrow or steal a prelube so. PRELUBE IS A MUST!!! You can do it by rotating the oil pump, but that doesn't work as well since you need the distributer in to really do it right. Do you feel up to all of this??? Let me know when you get that far.
Re: 454 engine thump Johnny 8-1-02  
Could it be that when the crank kit was installed it didn't fix the problen that is why it was all warm and ready to go when I got to the repair shop? What do you think?
Re: 454 engine thump Robert 8-1-02  
Just a long shot, but could it be possible that they didn't even install a crank kit? One thing that raised a flag for me was why were they so quick to offer a crank kit without really troubleshooting the noise first? Doesn't that make a person wonder?
Re: 454 engine thump or rap Roland Cook 5-31-04  
Hi there,
We have a 1984 Overland 29 ft RV with a chev 454 cc engine..It only has about 52,000 miles on it..We purchased it in 1992 and it had about 21,000 miles on it..We only average about 3,000 miles a year on it and concientiously change oil and filters about every 3,00miles..
Ive added a electric fuel pump in addition to the mechanical pump...Pulled spark plugs after 14,000miles{R 44T AC plugs.045 gap...
The gap was still >045 but all plugs were sooty black...Needless to say mileage not too good...
Engine seems to have power and starts good cold However typical 454 hard start when hot}
My problem is: picked up a thump or rap in the engine...Sounds like it is coming from top rear of head...
Want to make 2000 mile trip in June and wonder if that is possible..With Engine cover in place hard to hear noise...

Thank you sincerely
Another senior citizen Roland Cook
Re: 454 engine thump bill jenkins 9-8-06  
You should be at a absolute min. of 20 psi.This would be with alot of miles. How many miles? If it has set alot and doesn't have alot of miles, could be oil pump. What oil do you run? Bill
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